Process for producing anionic metal sulfonates

ABSTRACT

A PROCESS FOR PRODUCING ANIONIC METAL SULFONATES IS DISCLOSED WHEEIN AN ANIONIC METAL OXIDE OR HYDROXIDE IS REACTED WITH A HIGH BOILING ALCOHOL TO FORM THE CORRESPONDING ALKOXIDE. THE ALKOXIDE SO FORMED IS THEN REACTED WITH AN OIL-SOLUBLE SULFONIC ACID TO FORM THE DESIRED ANIONIC METAL SULFONATE. THE REACTIONS FOR THE FORMATIONS OF THE SULFONATE COMPOUND ARE CARRIED OUT IN THE PRESENCE OF A NONVOLATILE CARRIER COMPOUND.

United States Patent O 3,773,813 PROCESS FOR PRODUCING ANIONIC IVIETAL SULFONATES Mack W. Hunt, Ponca City, Okla, assignor to Continental Oil Company, Ponca City, Okla. No Drawing. Filed May 14, 1971, Ser. No. 148,263

Int. Cl. C07f 9/00, 9/90 US. Cl. 260-429 K 10 Claims ABSTRACT OF THE DISCLOSURE A process for producing anionic metal sulfonates is disclosed wherein an anionic metal oxide or hydroxide is reacted with a high boiling alcohol to form the corresponding alkoxide. The alkoxide so formed is then reacted with an oil-soluble sulfonic acid to form the desired anionic metal sulfonate. The reactions for the formations of the sulfonate compound are carried out in the presence of a nonvolatile carrier compound.

BACKGROUND OF THE INVENTION This invention relates to anionic metal sulfonates. In one aspect the invention relates to a process for producing anionic metal sulfonates. In yet another aspect the present invention relates to a method for producing anionic metal sulfonates from anionic metal oxides or hydroxides. In still another aspect the present invention relates to the in situ formation of an alkoxide which is then reacted with an oil-soluble sulfonic acid to form the desired anionic metal sulfonate. The alkoxide formed in situ results from the reaction between an anionic metal oxide or hydroxide and a high boiling alcohol.

BRIEF DESCRIPTION OF THE PRIOR ART In recent years it has been found that superior standards for spectrographic equipment can be prepared from oil-soluble metal sulfonates and metal dispersions in such sulfonates by dissolving such materials in predetermined quantities in a suitable solvent. Such standards have exhibited indefinite shelf life and any combination of metals can be combined without precipitation of the metal constituents.

Further, dispersions containing certain anionic metal sulfonates have acquired considerable importance as additives in fuels and lubricating oil. Such dispersions have been highly useful as additives to other materials where the problem of suspending insoluble waste materials formed in the utilization of the material and also the problem of corrosion inhibition is met. When the anionic metal sulfonates are employed as additives for use in internal combustion engine lubricating compositions, such agents function to effectively disperse or peptize the insolubles formed by the fuel combustion, oil oxidation, or similar conditions obtained during the operation of the engine.

Thus, while the use of anionic metal sulfonates have been established and recognized, problems have been encountered in the production of such anionic metal sulfonates. A need has long been recognized for an improved process for the production of anionic metal sulfonates from readily available chemical compounds, and it is to such a process that the present invention is directed.

3,773,813. Patented Nov. 20, 1973 "ice OBJECTS OF THE INVENTION An object of the present invention is to provide an improved process for the production of anionic metal sulfonates. Another object of the present invention is to provide an economical, dependable, and efficient method for preparing anionic metal sulfonates from readily available chemical compounds. Another object of the present invention is to provide an improved method for the preparation of vanadium sulfonate which is suitable as an analytical standard while at the same time providing an oil-soluble source of vanadium.

These and other objects, advantages, and features of the present invention would be apparent to those skilled in the art from a reading of the following detailed description.

SUMMARY OF THE INVENTION According to the present invention I have found a process for producing anionic metal sulfonates which basically involves two reactions in proceeding from the raw materials utilized to the final anionic metal sulfonate. In the first of these reactions an anionic metal oxide or hydroxide is reacted with a high boiling alcohol to produce the alkoxide corresponding to the alcohol constituent employed. As the alkoxide constituent is formed it reacts with an oil-soluble sulfonic acid to produce the desired anionic metal sulfonate.

Further according to the invention I have found vanadium sulfonate can readily be prepared from vanadium pentaoxide by reacting the vanadium pentaoxide with an alcohol having a boiling point of at least degrees C. to form the resulting alkoxide which corresponds to the alcohol constituent. As the alkoxide is formed it reacts with an oil-soluble sulfonic acid to produce the desired vanadium sulfonate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Anionic metal oxides and hydroxides react extremely slow with acid materials, especially organic acids. Therefore, in converting such anionic metal oxides or hydroxides to a sulfonate compound a different system must be employed. Likewise, when water or alcohols, such as methanol and ethanol, are employed in the reaction system, substantially no sulfonate product is formed. However, I have now found that anionic metal oxides or hydroxides can readily be converted to an anionic metal sulfonate by a novel process which basically involves two reactions in proceeding from the raw materials utilized, e.g. anionic metal oxide and hydroxide, to the final anionic metal sulfonate. Basically the reactants are all to be charged to a single reaction vessel at the start of process so that the product of the first reaction, e.g. the alkoxide, is formed in situ. As the alkoxide forms it immediately reacts with the oil-soluble sulfonic acid to form the desired anionic metal sulfonate. The formation of the alkoxide is facilitated by the reaction of the alkoxide with the oil-soluble sulfonic acid.

The process of the present invention can be carried out in either a batch-type or continuous process. However, for simplicity reasons a batch process will be described in detail. In a batch-type operation the anionic metal oxide or hydroxide is mixed with the high boiling alcohol constituent, the oil-soluble sulfonic acid constituent and the nonvolatile carrier constituent in areaction vessel which is equipped with stirring and heating means. The amount of reactants employed will vary widely but the alcohol constituent is added in at least a stoichiometric amount based on the anionic metal oxide or hydroxide. Generally, it is desirable that the alcohol be present in a stoichiometric excess. This excess generally ranges from about 5 to 50% by weight in excess of the stoichiometric amount as determined by the amount of anionic metal oxide or hydroxide. Once the reactants have been introduced into the reaction vessel the reactants are thoroughly agitated and the reaction mixture is heated to a temperature slightly below the boiling point of the high boiling alcohol constituent. During such heating period it should be noted that the azeotropic removal of water, formed by the reaction of the alcohol with either the anionic metal oxide or the anionic metal hydroxide, is an important feature of this step. It is important to remove such water so that the equilibrium reaction is shifted to allow the dominant formation of the alkoxide constituent. The period of time required for the formation of the alkoxide constituent can vary widely but generally will be within a period of time of from about 1 to hours.

The second reaction of the process is the reaction between the alkoxide so formed and the oil-soluble sulfonic acid to produce the anionic metal sulfonate. The amount of oil-soluble sulfonic acid employed will vary depending upon the amount of anionic metal sulfonate formed which in turn is dependent upon the amount of the anionic metal oxide or hydroxide constituent and the alcohol constituent initially employed. However, the amount of oilsoluble acid will be dependent solely upon the amount of the alkoxide since the alkoxide should be present in stoichiometric excess with the oil-soluble sulfonic acid. The excess generally will range from about 5 to 50 weight percent of the stoichiometric amount of said alkoxide.

The reaction mixture containing the alkoxide and the oil-soluble sulfonic acid is heated to a temperature within the range of about 75 degrees C. to 150 degrees C. to allow formation of the desired anionic metal sulfonate. The heating period is continued for a period of time generally within the range of about 1 hour to hours. It has been found necessary to employ the elevated temperatures if one desires to form the anionic metal sulfonate by process of the present invention. Especially desirable results have been obtained wherein the heating period is conducted under reflux conditions for a period of time from about minutes to five hours to insure substantially complete reaction between the alkoxide constituent and the oil-soluble sulfonic acid constituent. After the reaction has been completed the nonvolatile carrier, which contains the anionic metal sulfonate can be purified additionally by any suitable means such as filtration and the like. The purified product contains from about 20 to 90 weight percent of the anionic metal sulfonate in the nonvolatile carrier. In addition, additional purification steps for removal of solvents which may be present can be carried out. Such purification procedures involve heating the reaction mixture to a temperature of from about 125 degrees C. to 175 degrees C. and stripping the product with an inert gas, such as nitrogen, for a period of time of from about 10 minutes to 2 hours. In addition, it should be evident that inert solvents can be employed to facilitate the mixing of the reactants during both the initial reaction period and the second or subsequent reaction period. For example, the oil-soluble sulfonic acid can be diluted with a volatile solvent such as petroleum naphtha or hydrocarbons, such as hexane, heptane, octane, toluene, benzene or xylene. The use of such volatile solvents is merely to enhance the mixability of the sulfonic acid constituent into the reaction mixture and the solvent will be stripped due to the heating steps incurred in the process as described above.

In practicing the process of the present invention for the preparation of anionic metal sulfonates from anionic metal oxides or hydroxides any suitable anionic metal oxide or hydroxide can be employed. Examples of suitable anionic metal constituents are the oxides or hydroxides of boron, silicon, phosphorus, arsenic, selenium, scandium, yttrium, lanthanum, titanium, zirconium, vanadium, gold, and antimony. Desirable results have been obtained wherein vanadium pentaoxide and antimony oxide are employed as the anionic metal oxide.

The alcohols which are suitable for use in the process of the present invention are those which have a boiling point of at least degrees C. and in which the metal alkoxides have an appreciable solubility. I have found suitable alcohols to be the following: aliphatic monohydric alcohols having from 4 to about 6 carbon atoms, monoethers of ethylene glycol containing not more than 8 carbon atoms, and monoethers of diethylene glycol containing not more than 8 carbon atoms. Preferred glycol ethers are the monoethyl ether of ethylene glycol and the monomethyl ether of ethylene glycol. These materials are available commercially under the trademarks Cellosolve and methyl Cellosolve. The monoethyl ether of diethylene glycol is available commercially under the trademark Carbitol.

The monoethers of ethylene glycol are also known as alkoxy alkanols, and more specifically as alkoxy ethanols. These materials have the generic formula,

ROCH CH OH,

where R is a C to C hydrocarbon group. Similarly, the monoalkylether of diethylene glycol has the generic formula, HOCH CH OCH CH OR, where R is a C to C hydrocarbon group.

In conducting the azeotropic removal of water, it may be desirable to employ a known azeotroping agent, such as benzene or toluene. The use of such a material is necessary only when the alcohol employed does not form a favorable azeotrope with water. By favorable azeotrope is meant one which contains a relatively large amount of water.

Suitable oil-soluble hydrocarbon sulfonic acids include alkane sulfonic acid, aromatic sulfonic acid, alkaryl sulfonic acid, aralkyl sulfonic acid, and the natural petroleum mahogany sulfonic acids. The mahogany sulfonic acids include any of those materials which may be obtained by concentrated or fuming sulfuric acid treatment of petroleum fractions, particularly the higher boiling lubricating oil distillates and white oil distillates. The higher molecular weight petroleum oil-soluble mahogany sulfonic acids are condensed-ring compounds, which condensed-rings may be aromatic or hydroaromatic in nature. Alkyl and/ or cycloalkyl substituents may be present in the mahogany sulfonic acids.

The term oil-soluble sulfonic acids, as used herein, refers to those materials wherein the hydrocarbon portion of the molecule has a molecular weight in the range of about 300 to about 1,000. Preferably, this molecular weight is in the range of about 370 to about 700. These oil-soluble sulfonic acids can be either synthetic sulfonic acids or the so-called mahogany or natural sulfonic acids. The term mahogany sulfonic acid is believed to be well understood, since it is amply described in the literature. The term synthetic sulfonic acids refers to those materials which are prepared by sulfonation of hydrocarbon feedstocks which are prepared synthetically. The synthetic sulfonic acids can be derived from either alkyl or alkaryl hydrocarbons. In addition, they can be derived from hydrocarbons having cycloalkyl (i.e., naphthenic) groups in the side chains attached to the benzene ring. The alkyl groups in the alkaryl hydrocarbons can be straight or branched chain. The alkaryl radical can be derived from benzene, toluene, ethyl benzene, xylene isomers, or naphthalene.

An example of a hydrocarbon feedstock which has been particularly useful in preparing synthetic sulfonic acids is a material known as postdodecylbenzene. Postdodecylbenzene is a bottoms product of the manufacture of dodecylbenzene. The alkyl groups of postdodecylbenzene are branched chain. Postdodecylbenzene consists of monoalkylbenzenes and dialkylbenzenes in the approximate mole ratio of 2:3 and has typical properties as follows:

Specific gravity at 38 degrees C 0.8649

An example of another hydrocarbon feedstock which is particularly useful in preparing synthetic sulfonic acids is a material referred to as dimer alkylate. Dimer alkylate has a long branched-chain alkyl group. Briefly described, dimer alkylate is prepared by the following steps:

(1) dirnerization of a suitable feedstock, such as cat poly gasoline; and

(2) alkylation of an aromatic hydrocarbon with the dimer formed in step (1).

Preferably, the dimerization step uses a Friedel-Crafts alkylation sludge as the catalyst. This process and the resulting product are described in U.S. Pat. No. 3,410,925.

An example of another hydrocarbon feedstock which is particularly useful for preparing synthetic sulfonic acids which can be used in my invention is a material which I refer to as NAB Bottoms. NAB Bottoms are predominantly di-n-alkyl aromatic hydrocarbon wherein the alkyl groups contain from 8 to 18 carbon atoms. They are distinguished primarily from the preceding sulfonation feedstocks in that they are straight chain and contain a large amount of disubstituted material. A process of preparing these materials and the resulting product are described in application Ser. No. 62,211, filed Aug. 7, 1970, and being a continuation-in-part of application Ser. No. 529,284, filed Feb. 23, 1966, and now abandoned. Application Ser. Nos. 62,211 and 529,284 have the same assignee as the present application. The product is also described in U.S. Pat. No. 3,288,716, which is concerned with an additional use for the product, other than sulfonation feedstock. Another process of preparing these materials is described in application Ser. No. 53,352, filed Aug. 6, 1970, now U.S. Pat. 3,662,012, and having the same assignee as the present application. Application Ser. No. 53,352 is a continuation-in-part of application Ser. No. 529,284. Still another process of preparing a di-n-alkaryl product is described in application Ser. No. 104,476, filed Jan. 7, 1971, now abandoned, which is a continuatiominpant of application Ser. No. 52 11,794, filed Jan. 20, 1966, and now abandoned.

In order to make my disclosure even more complete, U.S. Pat. No. 3,410,925 and application Ser. Nos. 53,352; 62,211 and 104,476, are made a part of this disclosure.

The oil-soluble sulfonic acids are preferred for use in my process.

In addition to the sulfonic acids derived from the foregoin described hydrocarbon feedstock, examples of other suitable sulfonic acids include the following: monoand poly-wax-substituted naphthalene sulfonic acid, dinonyl naphthalene sulfonic acid, diphenyl ether sulfonic acid, naphthalene disulfide sulfonic acid, dicetyl thianthrene sulfonic acid, dialauryl betanaphthol sulfonic acid, dicapryl nitronaphthalene sulfonic acid, unsaturated paraffin wax sulfonic acid, hydroxy substituted paraffin wax sulfonic acid, tetraamylene sulfonic acid, monoand poly-chlorosubstituted paraffin wax sulfonic acid, nitrosoparalfin wax sulfonic acid, cycloaliphatic sulfonic acid such as lauryl-cyclohexyl sulfonic acid, monoand polywax-substituted cyclohexyl sulfonic acid, and the like.

The corresponding hydrocarbon sulfonic acid is usually prepared by treating the hydrocarbon with concentrated sulfuric acid, fuming sulfuric acid or sulfur trioxide. The sulfonation of hydrocarbons is Well known and details need not be given.

In order to disclose more clearly the nature of the present invention the following example is given. It is to be understood that the example is for illustrative purposes only and is not to be construed as undue limitations upon the invention.

Example 1 A 12-liter, 3-necked flask was charged with the following mixture:

6,000 g. dialkylbenzene sulfonic acid having average molecular weight of 500 diluted with about 50% hexane 270 g. vanadium pentaoxide 2,000 g. methyl Cellosolve 1,200 g. pale oil The above was heated with mixing. The solvents were removed to degrees C. and then an additional 2,000 g. of methyl Cellosolve was added. Heating was continued and the solvents were removed to a pot temperature of degrees C. The mixture was then allowed to reflux for about one hour. During this period the vanadium pentaoxide slowly dissolves and the product becomes bright and clear. Following the reflux step, the solvents were removed to degrees C. and the product stripped with N; for about 45 minutes. The polish filtered product contained 1.79 percent vanadium. This percent vanadium is approximately theoretical based on vanadium pentasulfonate.

Example 2 l-liter, 3-necked creased flask was charged with the following mixture:

200.0 g. mixture of sulfonic acids which contains about 40% of dialkylbenzene sulfonic acid having an average molecular weight of 440 and 60% of monoalkaryl sulfonic acid having an average molecular weight of 510 (the mixture is diluted with about 70% hexane) 53.6 g. 80 Pale Oil 21.2 g. antimony oxide (2 times stoichiometric) 125.0 g. methyl Cellosolve 18.0 g. Distilled water The above was heated with mixing to the reflux temperature. The solvents were removed to 120 degrees C. and then the mixture was refluxed for 2 hours. Following the reflux step, the solvents were removed to 150 to degrees C. and the product stripped with N for about 30 minutes. The polish filtered product contained about 6.29 percent antimony. This percent antimony is approximately theoretical based on antimony sulfonate.

The above examples clearly indicate the preparation of an anionic metal sulfonate by the process of the present invention.

Having thus described the invention, I claim:

1. A process for producing anionic metal sulfonates which comprises:

(a) reacting an anionic metal compound selected from the group consisting of anionic metal oxides and hydroxides wherein said metal constituent is selected from the group consisting of boron, silicon, phosphorus, arsenic, selenium, scandiu-m, yettrium, lanthanum, titanium, zirconium, vanadium, gold, and

antimony with an alcohol having a boiling point of at least 100 C., at a temperature below the boiling point of said alcohol for an effective period of time to allow formation of an alkoxide corresponding to said alcohol, said alcohol being present in an amount in excess of the stoichiometric amount required to completely react with said anionic metal compound;

(b) azeotropically removing water formed during the formation of said alkoxide;

(c) reacting said alkoxide with an oil-soluble sulfonic acid, said alkoxide being present in an amount in excess of the stoichiometric amount required to completely react with said acid, in the presence of a nonvolatile carrier at a temperature within the range of from about 50 degrees C. to 150 degrees C. for an effective period of time to allow formation of said anionic metal sulfonate; and

(d) recovering said nonvolatile carrier which contains from about 20 to 90 weight percent of said anionic metal sulfonate.

2. The method of claim 1 wherein said alcohol is pres ent in a stoichiometric excess ranging from about to 50 weight percent of said stoichiometric amount and said alkoxide is present in a stoichiometric excess ranging from about 5 to 50 weight percent of the stoichiometric amount of said alkoxide.

3. The process of claim 2 wherein said alcohol is selected from the group consisting of aliphatic monohydric alcohols having from 4 to about 6 carbon atoms, monoethers of ethylene glycol containing not more than 8 carbon atoms, and monoethers of diethylene glycol containing not more than 8 carbon atoms.

4. The process of claim 3 wherein said alcohol is a monoether of an ethylene glycol selected from the group consisting of a monoethyl ether of ethylene glycol and a monomethyl ether of ethylene glycol.

5. The process of claim 4 wherein said oil-soluble sulfonic acid is diluted with an effective amount of a volatile solvent to reduce the viscosity of said oil-soluble acid and to facilitate the mixing of the sulfonic acid with the alkoxide.

6. The process of claim 5 wherein said reaction between said oil-soluble sulfonic acid and said alkoxide is carried out under reflux conditions for a period of time of from about 30 minutes to 5 hours.

7. The process of claim 6 which includes the step of purifying the nonvolatile carrier containing the anionic metal sulfonate by stripping same with an inert gas for a period of time of from about 20 minutes to 2 hours.

8. The process of claim 7 wherein said oil-soluble sulfonic acid is selected from the group consisting of alkane sulfonic acids, aromatic sulfonic acids, alkaryl sulfonic acids, dialkaryl sulfonic acids, aralkyl sulfonic acids, and natural petroleum mahogany sulfonic acids.

9. The process of claim 8 wherein said anionic metal compound is vanadium pentaoxide, said alcohol is a monomethyl ether of ethylene glycol, said nonvolatile carrier is pale oil, and said oil-soluble sulfonic acid is an alkaryl sulfonic acid diluted with hexane, said alkaryl sulfonic acid having a molecular weight in the range of about 350 to 700.

10. The process of claim 8 wherein said anionic metal compound is antimony oxide, said alcohol is a monomethyl ether of ethylene glycol, said nonvolatile carrier is pale oil, and said oil-soluble sulfonic acid is a mixture of a dialkaryl sulfonic acid and a monoalkaryl sulfonic acid diluted with hexane, said dialkaryl sulfonic acid having an everage molecular weight of about 440 and said monoalkaryl sulfonic acid having an average molecular weight of about 510.

References Cited UNITED STATES PATENTS 2,257,009 9/1941 Hill 260429 R 2,779,784 1/1957 Sharrah 260-505 N 2,865,957 12/1958 Logan 260429.9 3,021,280 2/1962 Carlyle 25233 3,222,251 12/1965 Wyckoif et a1 260-429 R 3,242,080 3/1966 Wiley et a1. 25233 3,250,710 5/1966 Hunt 252-33 OTHER REFERENCES Bradley: Progress in Inorganic Chemistry, vol. II (1960), Interscience Publishers, New York, N.Y., pp. 305-6.

DANIEL E. WYMAN, Primary Examiner A. P. DEMERS, Assistant Examiner U.S. Cl. X.R.

252 33; 260-4292, 429.3, 429.5, 429.9, 430, 440,446, 448.2 N 606.5 B, 606.5 P, 607 R; 356-74 

